In order to reduce the power consumption of liquid crystal televisions and improve the contrast thereof, a dynamic backlight control method, i.e., a local backlight control (also called local dimming) method, is generally used to divide backlight Liquid Emitting Diodes (LEDs) into several regions, and LEDs in each region are individually controlled according to average display brightness of a picture. This conventional method has disadvantages in that different numbers of backlight blocks have different display brightness. For example, brightness of one LED block when the LED block is lighted up is different from brightness of two LED blocks when the two LED blocks are lighted up. As shown in FIG. 9, for an L255 gray-scale picture, when one LED block is fully lighted up, brightness of a unit is measured to be 200 nits, and when two LED blocks are fully lighted up, the brightness of the unit is measured to be 300 nits, which results in a difference between display brightness.
The conventional local backlight control method only carries out analysis on input data for picture brightness, and then carries out driving of the backlight LEDs, which results in reduction in the picture contrast and the display effects.